1. Periodic solutions of the forced pendulum equation;Castro,1980
2. Periodic oscillations of forced pendulum-like equations;Mawhin,1982
3. Points fixes, points critiques et problèmes aux limites;Mawhin,1985
4. Multiple solutions of the periodic boundary value problem for some forced pendulum-type equations;Mawhin;J. Differential Equations,1984
5. Ordinary Differential Equations. Stability and Periodic Solutions;Rouche,1980